The present invention relates to a communication apparatus that allows a controller and a transmitter/receiver module for human body communication to enter a normal operation state from a stand-by mode by sensing contact or approach of human body by using a method of transmitting a signal between devices which are mounted on or placed near the human body as a communication medium, and a method thereof. Further aspects of the invention relate to a human body communication apparatus that is in contact with a human body to conduct a communication, and more particularly, to a human body communication apparatus that senses the contact with or proximity to a human body to operate a controller and a transceiver module, both of which are used for human body communication and are in a standby mode, into a normal state.
Aspects of the present invention were supported by the IT R&D program of MIC/IITA [2006-S-069-03, Development of Wearable System Using Physiological Signal Processing].
A communication input/output apparatus which senses the contact of the human body may apply to mobile devices such as hand phones, MP3 players, digital cameras, etc. A conventional system for human body communication, in which devices mounted on or placed near a human body communicate with one another through the human body as a communication medium, allows a communication channel to be formed when in contact with the human body. However, it is uncertain when a device embedded with a human body communication module will come in contact with the human body, and thus a signal needs to be periodically checked so as to find out whether a communication channel has been formed between corresponding devices. In this case, even if there is no contact with the human body, the device itself cannot recognize whether there is contact with the human body. Therefore, not only a receiving-end circuit that converts a weak signal received through the human body into a digital signal that can be processed by a micro-controller but also a micro-controller that performs a control operation has to be constantly or periodically in a wake-up state to reduce power consumption.
When a transmitter has data to be sent, even if a human body communication micro-controller initially operates after data is output to an external control signal or a designated memory area, a transmitter circuit that converts the digital signal received from the micro-controller into a signal to be output to the human body has to be operated in a normal state until contact with the human body has been made. That is, in order to check whether a channel is formed, the transmitter circuit has to operate even if there is no contact with the human body, which leads to unnecessary power consumption.
As described above, power is unnecessarily consumed because a transmitter/receiver circuit and a micro-controller for controlling the transmitter/receiver circuit have to constantly or periodically be in the normal state so as to determine whether a channel has been formed in transmitting and receiving processes even if there is no contact with the human body.
In further detail, in the case of the transmission unit including data to be transmitted, the micro controller used for human body communications applies an external control signal and data to a predetermined memory area. Therefore, a receiving circuit for confirming whether communication channels are formed, as well as a transmission circuit, should continue to operate normally. Here, although the transmission circuit starts to operate, the transmission circuit has a function to convert a digital signal received from the micro controller into a signal for applying to the human body before the transmission circuit is in contact with the human body. That is, the transmission circuit and the receiving circuit are operated to confirm whether the communication channels are formed even when there is no contact with the human body. Therefore, the power is consumed unnecessarily in the conventional devices using human body communications.
As described above, the conventional human body communication apparatuses have a problem that the transmission and receiving circuits and the micro controller for controlling the transmission and receiving circuits should be always or periodically be in a normal operation mode even when the transmission and receiving circuits are not in contact with a human body. The transmission and receiving circuits should operate to confirm whether communication channels are formed. This indicates that power is unnecessarily consumed in the conventional human body communication apparatuses. Also, the communication input/output apparatus that may sense simple human body contact has a problem that the unnecessary power consumption is caused in modems and transceiver modules for human body communication since it is impossible to interpret the exact intention of a user when the user approaches the device for the purpose of other uses other than human body communications.
When there is no contact of a user with the human body communication apparatus having a contact sensor unit, the human body communication apparatus may reduce its consumption of electric power, which is used to judge whether the communication channels are formed, by applying the human body communication apparatus with a contact sensor unit to portable devices such as a hand phone. However, when a human body approaches and contacts with electrodes of the devices for the purpose of other operations, for example contacts for other uses of a user such as communications, listening to music, or taking photographs, these human body communication apparatuses sense the contact and approach to the human body, regardless of the intentions of a user, to generate a control signal. Therefore, there is a need to prevent the unnecessary power consumption since the human body communication apparatuses transmit/receive data to/from the external devices using the control signal.